Extensive phospholipid resorption from senescing leaves is not associated with phospholipid substitution in an oligotrophic heath

Abstract Background and aims In leaves, ~ 25% of phosphorus (P) is allocated to membrane phospholipids. A significant amount of leaf P is resorbed during leaf senescence to reduce plant P loss upon leaf abscission and fuel the growth of new leaves. High P resorption observed in plants on P depleted soils has been associated with extensive resorption of all P-fractions, including phospholipids, from senescent leaves. This high resorption of phospholipid-P could be associated with the substitution of phospholipids with non-P galactolipids and sulfolipids. Methods We evaluated whether high phospholipid resorption is associated with the substitution of phospholipids with non-P lipids by quantifying the total P, and intact membrane phospholipid, galactolipid and sulfolipid concentrations of mature and senescent leaves of nine co-occurring species (five families) associated with a severely P-poor soil in eastern Australia. Results Phosphorus resorption efficiency, defined as the percentage of P resorbed from senescing leaves per P content in mature leaves, was high across species ( c. 77 – 96%). Total membrane lipid content was substantially lower in senescent leaves than mature leaves across species, although, there was a tendency for resorption efficiency to be greater for non-P lipids ( c. 55 – 95%) than phospholipids ( c. 4 – 87%). Conclusion Exceptionally high rates of total and phospholipid P resorption from senescing leaves is not necessarily associated with the substitution of phospholipids with non-P lipids.